Magazine

Spotting Quakes Hours before the Shaking Starts

June 22, 2003

In an effort to predict earthquakes, seismologists have studied everything from ground uplift and changes in water temperature to unusual animal behavior and radon emission. None of these signs has proved reliable. But in 1989, they noticed something promising: On Oct. 18, three hours before a quake measuring 7.1 on the Richter scale struck Loma Prieta, Calif., there was a marked rise in extremely low frequency (ELF) fluctuations of the earth's magnetic field.

Luckily, scientists were on hand with measuring equipment. Now, for the first time, researchers are trying to assess ELF's predictive power. QuakeSat, a small satellite designed at Stanford University and QuakeFinder, a Palo Alto (Calif.) startup, could provide a global view of ELF fluctuations. Set to launch on June 30, it houses a magnetometer to detect ELF changes from 520 miles up. Initially, QuakeSat will record fluctuations to establish a baseline. Then, researchers will study how deviations from the norm correlate with quakes.

It's not yet clear whether the satellite will be able to measure ELF accurately against a noisy background of solar storms and man-made radio signals. Marijean T. Seelbach, CEO of QuakeFinder, believes that "some of the signals we expect to see are really interference." But once these are identified, she says, they can be factored out of the resulting data. Since hydrogen fuel cells emit only water as waste, their widespread adoption over the coming decades promises to cut emissions not only of greenhouse gases but also of pollutants that destroy earth's protective ozone layer. In a scenario described in the June 13 issue of Science, however, hydrogen that manages to leak out during production, shipment, or storage could actually speed up ozone depletion.

Capable of diffusing through metal, hydrogen gas is so tricky to contain that "about 10 to 20% of the current volume shipped" escapes, says John M. Eiler, a geochemist at California Institute of Technology and one of the paper's authors. In the stratosphere, increased levels of H2 start a chain reaction that destroys ozone. At the current rate of leakage, the study estimates, a global shift from oil to hydrogen would increase annual worldwide hydrogen emissions by four- to eightfold.

This study shouldn't scotch Utopian schemes for a Hydrogen Economy, though. "These are highly solvable problems -- but you have to plan for them," Eiler says. Already, engineers are working on leakproof ways to handle the gas. Doctors may one day use a variety of rapid prototyping techniques to build replacements for bones destroyed by injury or disease. The Office of Naval Research (ONR) in Arlington, Va., pioneered such techniques for making plastic, metal, and ceramic parts from digital designs. Biomedical engineers picked up the trend, making plastic plugs to replace pieces of damaged bone. Three years ago, the ONR teamed up with Advanced Ceramics Research Inc. in Tucson for more advanced applications.

To help a man with a smashed arm, for example, doctors could convert MRI or CT scans of bone segments in his good arm into code for the replacement part in the injured one. Code would be fed into rapid prototyping equipment, which would make the desired segment from a polymer coated with a thin layer of porous calcium phosphate.

In the following 18 months, says ACR's Ranji Vaidyanathan, bone cells would adhere to the implant, fill the pores in the ceramic, and break down the foreign material. Ultimately, all that would remain of the implant would be some of the original polymer core, which would be encased in sturdy bone tissue. ACR thinks the technique, which has already been tested in rats, could receive Food & Drug Administration approval in three or four years. -- Computer simulations can't tell who is likely to commit a crime or become a victim. But software developed at Carnegie Mellon University can predict -- one month in advance, and with 80% accuracy -- how many crimes in various categories are likely to occur in a 100-block area of a particular city. Funded by the research wing of the Justice Dept.'s National Institute of Justice, the CMU team built a computer model based on 10 years of crime data from Pittsburgh and Rochester, N.Y. They then ran thousands of forecasts for the month ahead, broken down into burglary, assault, car theft, and other categories. Even the researchers were surprised at how closely their model foretold the actual incidence of crime.

-- Scientists at London's St. George's Hospital Medical School have found a way to kill the parasite that causes malaria where it lurks inside red blood cells. The trick, described in the Proceedings of the National Academy of Sciences, involves disabling a "transport protein" the parasite uses to absorb glucose from its surroundings. The scientists, led by professor Sanjeev Krishna, hope to use this mechanism to develop new medicines that might work against drug-resistant strains.